The invention relates to a data acquisition circuit that receives the analog output of a line scan camera and provides it in a digital form for use by a computer.
Line scan cameras are used to scan scenes in a one-dimensional manner, one line of pixels at a time. They are often used to check the size or shape of objects traveling on a conveyor belt. They typically employ a linear array of photocells, each photocell providing a pixel of the line. The photocells are triggered simultaneously to detect light intensity at the same time, and the individual outputs of the photocells are accessed in a sequential manner, starting at one side of the linear array and going to the other. The output of the line scan camera is an analog signal having a magnitude related to intensity.
The analog output of the line scan camera is converted into digital form by an analog-to-digital converter. A timing signal from the line scan camera is used to correlate the value of the analog output at a given time with a particular photocell of the array, so that a series of digital outputs is obtained, each output representing the intensity detected at a particular photocell. The digital outputs can then be temporarily stored for use by a computer.